Cutaneous Haemorrhages

General Remarks
Blood may be effused into the skin under a variety of circumstances. The occurrence may take place as an idio-pathic condition spontaneously; or secondarily in connection with other diseases of the skin. The blood-vessels may be ruptured, and so permit the escape of blood, or the blood globules may escape bodily through the actual vessel walls. The usual cause of rupture is traumatic injury. The haemorrhagic spots receive different names according to their size and shape. When they are small, in the form of red points, they are called petechiae; when larger, and more or less linear, vibices; when large in the form of bruises, ecchymosis; and when the blood collects in the form of a distinct tumor, haematomata.

The secondary forms of cutaneous haemorrhage occur in connection with typhus, measles, scarlatina, and variola, the early eruptions of which may severally be more or less haemorrhagic, the hyperaemia being accompanied by actual haemorrhage into the skin. The eruption of several of the ordinary inflammatory diseases of the skin also are sometimes complicated by a certain amount of effusion of blood. Other conditions under which cutaneous haemorrhages arise are altered states of the blood current, such as impurifications by bile products, stasis of the capillaries produced in connection with kidney and heart disease, etc.


It is only to haemorrhage occurring as a primary and independent disease that the term purpura is applied, and this we will now describe.